The present invention relates to a fuel injection nozzle for use in an internal combustion engine.
There is generally known a fuel injection nozzle of so-called spiral swirl type in which fuel swirled in a nozzle body flows into an inlet of an orifice formed through the nozzle body and then sprays the swirled fuel out of an outlet of the orifice into a combustion chamber within an engine cylinder.
Japanese Patent Application First Publication No. 60-142051 discloses one example of such spiral swirl-type fuel injection nozzle. The fuel injection nozzle includes a nozzle body having an orifice disposed coaxially with the nozzle body. The orifice has an outlet contoured by a circumferential edge portion of the orifice and disposed on a plane normal to a center axis of the orifice. The orifice sprays a fuel such that the sprayed fuel constitutes a body having a center axis aligned with a center axis of the nozzle body.
The prior art fuel injection nozzle has been arranged in a limited space of the engine in such a way that a fuel sprayed from the orifice is directed to a central portion of a piston head in the engine cylinder. During spraying, intake valve heads within the engine cylinder are sprayed to be contacted with the fuel. The contact of the sprayed fuel disturbs smooth operation of the intake valves, resulting in decrease of combustion efficiency.
There have been made attempts to effectively spray fuel toward the piston head and prevent the intake valve heads From being in contact with the fuel sprayed. Japanese Patent Application First Publication No. 60-261975 discloses a spiral swirl-type fuel injection nozzle. This fuel injection nozzle includes a nozzle body having an orifice provided at a predetermined angle with respect to a center axis of the nozzle body. The orifice has a center axis offset from the center axis of the nozzle body. The fuel sprayed through the orifice forms a sprayed fuel body having a center axis offset from the center axis of the nozzle body. This arrangement allows the fuel to spray toward the piston head within the engine cylinder. However, since the center axis of the orifice is offset from the center axis of the nozzle body, the swirl of the fuel decreases during its flowing through the orifice. Such a decrease of the swirl leads to disturbance of spraying the fuel in the form of fine particles.
An object of the present invention is to provide a fuel injection nozzle for use in an internal combustion engine which serves for improving combustion efficiency.